to block texas from enacting state paased last year... wwich equires registered voters to posssss as well a valid, state-issuee photo i-d. proponents say it'll eeforrement officer disagrees.- holder says: "[w]e objected to a photo id requirement in texas because it would have had a disproportiooate impact on hispanic voters." to prove that, the department of justice retained as an expert witness... harvard university professor of government stephen ansolabehere... who in turn relied on a data fiim called catalyst to supply statistical iiformation... such as the percentages of whhtes and minorities in texas who are registered to vote."i had [previously] conducted several studies using the catalist data [the rofessor testified] anda"aa&i found identified by catalist as black, white oo hispanic identified themselves in the race projected by catalist."e rosenberg says: "if there was a perception that catalist was cooking the books in any way, you know,,they would llse all their clients, right? i pean this is -- they're all about integrity.""